Millennials in charge are at an age where they vote and have all the bills.
Like the Boomers before them, the between group of Millennials need to pay for kids college and retire one day. Promotions, raises, and new jobs coming into the heights of their careers taxes are not on their wish list.
The Millennials are a larger generation than the Boomers. This explains the demographic shifts in the last election to a good degree. Other groups are either smaller or less likely to vote.